Devices for delivering medicament to a patient are known in the art. One type of drug delivery device is identified as a wearable infusion device or patch pump. These devices are intended for attachment to a patient's skin for self-administration of a medicament, such as insulin. Wearable infusion devices are generally intended for patients who prefer only a single needle insertion in a 2-3 day period, rather than 8-12 normal insulin injections in the same period. The advantage of wearable infusion devices is that the patient is subjected to fewer needle sticks than other delivery methods, such as a syringe or an injection pen.
When the wearable infusion device is attached to a patient's skin and activated, a hollow needle from the infusion device is injected into the patient's skin, and a drive mechanism to administer the medicament to the patient via the needle is actuated. Typically, in an infusion device, the needle is in communication with a reservoir containing the medicament. U.S. Pat. No. 5,858,001 to Tsals et al., incorporated herein by reference, discloses an infusion device which is activated by a swivel action of a main body containing a reservoir of medicament in relation to a member attached to a patient's skin. Upon activation, the device of Tsals et al. is primed and causes a needle to penetrate the skin of a patient and administer the medicament. The needle remains attached to the skin until the device is removed. Other types of infusion devices are known in the art.
In some infusion devices, activation can be awkward or imprecise, causing discomfort to the user. For instance, in the device of Tsals et al., a pivoting action of a main body containing the medicament reservoir and the needle against a member attached to the patient's skin is required, which requires additional space for activation, possible discomfort to the user, possible exposure of the needle to unwanted contact, and other related problems. Prior art infusion devices may also be prone to accidental activation since they sometimes lack safety devices that can prevent accidental activation.
Accordingly, a need exists for an improved infusion device, particularly a wearable infusion device, in which activation of the device is discrete, sanitary and accurate, and that minimizes the likelihood of unintended activation.